Sweet spot for Samsung TCCDs

Hey guys,
I wanted to know if you guys found some sord of "sweetspot" for these chips.
What I mean is lowest possible timings with what voltage.
I'm currently running my PQIs @ 277 and 3-3-3-8 1T @ 2.75v, Memtest86+ #5 comes clear of errors so does P95.
At 280 (same timings, same voltage) memtest86+ test #5 comes clear but P95 fails after an hour or so.

Do you think it needs more voltage?

Thanks for your input,
Suma.

i need to pump 2.85v in mine to get it to run at max, i've found that running cas2.0 is best for my setup, 235mhz 2-3-3-5 beats 260mhz 2.5-3-3-6 in everything eccept sandra bandwidth bench, 218mhz at 2-2-2-5 doesn't so as well as 235 2-3-3-5 either